Design and Optimization of LC Oscillators

We present a method for optimizing and automating component and transistor
sizing for CMOS LC oscillators. We observe that the performance measures can be
formulated as posynomial functions of the design variables. As a result, the LC
oscillator design problems can be posed as a geometric program, a special type
of optimization problem for which very efficient global optimization methods
have recently been developed. The synthesis method is therefore fast, and
determines the globally optimal design; in particular the final solution is
completely independent of the starting point (which can even be infeasible),
and infeasible specifications are unambiguously detected. We can rapidly
compute globally optimal trade-off curves between competing objectives such as
phase noise and power.